Vulcanizing apparatus



May 24, 1932.

C. E. MAYNARD VULCANIZING APPARATUS Filed Feb. 19, 1930 IN VEN TOR. C/wf/cc 119 01 Maynard.

ATTORNEY.

Patented May 24, 1932 UNITED STATES CHARLES EDGAR MAYNARD, OF NORTHAMPTON, MASSACHUSETTS, ASSIGNOR TO THE PATENT I OFFICE FISK RUBBER COMPANY, OF CHICOPEE FALLS, IvIASSACI-IUSETTS, A CORPORATION MASSAC'HUSETTS VULCANIZING APPARATUS This invention relates to apparatus for the vulcanization of inner tubes and particularly to improvements in that type of vulcanizer in which the tube is cured while in circular condition and while the interior of the tube is expanded by internal fluid pressure.

It is the practice in tube construction to add a strengthening pad of plied rubber and fabric material to that portion of the tube through which the valve stem projects. This added material gives the tube a much greater thickness at that portion with the result-that {the cure at that portion of the tube tends to Another cause for undercuring of the valve stem portion of the tube is due to a certain amount of heat loss incurred by the escape of air along the valve stem during the cure. Another loss is due to occasional leaks between the connection and the valve causing some of the air used for inflating the tube in the mold to be blown upon the mold.

It is an object of my invention to provide means by which the tube and valve pad may become completely and evenly cured.

In the drawings which illustrate one embodiment of my invention,

Fig. 1 is a cross-section through a tube vulcanizer taken at the valve stem portion of the mold and showing the invention in place therein and with a tube and bent valve stem in position;

Fig. 2 is a view taken substantially on line 22 of Fig. 1;

Fig. 3 is a view taken substantially on line 33 of Fig. 1;

Fig. 4 is a modification showing the adaption of my invention to molds with slidable valve stem block; and

Fig. 5 is a view taken substantially on line 55 of Fig. 4:.

In the drawings I have shown a tube mold 10, as one type of vulcanizer to which my invention may be applied, provided with steam chambers 11. The valve section of the mold has been bored at 12 to permit the insertion of a plug 13. This plug is provided with a steam chamber 14 fed by an inlet pipe 15 and outlet pipe 16. An opening in the plug 13, preferably provided with a bushing 17,

is adapted to fit a valve stem 18 of a tube 19. Although shown in the drawings as an angle stern, a straight stem 20 (dotted lines) may equally Well be usedin the embodiment shown. The opening orjbushing 17 Will hold the stem in its correct alignment with the tube and an adjustable stop 21 held by bracket 22 will hold the angle stem 18 in correct relation to its final position in the tube.

In Figs. 4 and 5 I have shown a mold 10 made with a slidable block 23 designed to accommodate tubes havin so-called gooseneck stems 24: and provided with a plug 25 with a steam chamber 26. The plug 25 is cut away at 27 where it is bounded by the slidable block 23. As in plug 13, the plug 25 is fed by an inlet pipe 28 and an outlet pipe 29. The block 23 itself may be, and preferably is, formed with a steam chamber 30 and fed by pipes 31 and 82.

The steam chambers formed in all the plugs described provide cavities closer to the valve stem opening and, even with steam at the same pressure as in chambers 11, heat that section in the vicinity of the stem sufiiciently for a complete cure. It has been found preferable, however, to provide a separate steam circulation for the plug to permit raising the pressure of the steam in the plug cavities somewhat higher than the pressure in chambers 11 since, as previously explained, there is a certain loss of heat about the valve stem that it may be necessary to compensate. With experimentation the difference in these pressures may be determined so as to have the valve pad portion completely cured at the same time the body of the tube 19 is completely cured.

Having thus described my invention, I claim:

1. A vulcanizing mold for inner tubes which comprises mold members provided with steam chambers, an opening in one of the mold members through which the valve stem of the tube is adapted to pass, an annular plug fitting in said opening and surrounding the valve stem, said plug being provided with an annular steam chamber and means to'supply steam tosaid annular chamber independently of the steam chambers of the mold members.

2. A vulcanizing mold for inner tubes which comprises mold members provided with steam chambers, an opening in one of the mold members, a plug fitting in said opening, an aperture in the plug through Which the valve stem of the tube is adapted to-pass, a steam' chamber formed in the plug and means'to supply steam to said last named chamber independently of the steam chambers of the'mold members.

3; A vulcanizing mold for inner tubes having valve stems which comprises mold members provided with steam chambers, an opening in one of the members through Which the valve stem is adapted to pass, a steam chamber surrounding said opening and means to supply steam to said last named chamber independently of the steam chambers of the mold members.

' CHARLES EDGAR MAYNARD. 

